Twenty years ago, when most of us thought of "diversity," the prefix "bio-" was attached to it, along with visions of nature. Today, diversity and inclusion (D+I) has become big business for corporate America and many other organizations, including associations.

That's because diversity has been shown to drive business success. According to a 2015 McKinsey report, companies in the top quartile for racial and ethnic diversity are 35 percent more likely to have financial returns above their respective national industry medians. Since the 1990s, the case for diversity has been supported by business data. In 1995, the Federal Glass Ceiling Commission [PDF] found that the stock market performance of companies that invested in glass-ceiling related issues was 2.5 times higher than other companies' performance. Racially diverse companies have 15 times more revenue than the least racially diverse, which explains why 40 percent of companies with $5 billion in revenue have diversity as a focus in recruitment, according to a Forbes Insights study [PDF].

Despite all the evidence supporting diversity as a business imperative, many organizations feel stuck in their diversity mission, in part because they do not know the difference between D+I.

What's the difference? Diversity is like being invited to sit at a table that is already set; inclusion is being asked to partner with the host to help set the table. If you have a diverse workforce but lack an inclusive workplace culture, you still have work to do to reap the full benefits of D+I.

Studies have shown people naturally create "in-groups" and "out-groups," based on similarities and differences. The more people perceive someone to be different, the less likely they are to feel comfortable with or trust that person, and they place the person in their out-group. This kind of categorization, while usually unconscious, can do significant damage in the workplace.

The manager who ignores complaints of insensitivity is just as guilty as the person who makes the offending comment or gesture.

While there are many benefits to an inclusive work environment, some organizations still operate with a mindset of exclusivity, creating barriers to inclusion that are difficult to overcome. Identifying these barriers in your organization is critical to success. When you knock them down, your whole organization will be better for it.

Selective Mentoring

Unconsciously, people are more likely to be invested in someone else's career development when they can see themselves in the colleague. This is why informal mentoring relationships are more challenging to create when there are more differences between colleagues.

Informal mentoring is a self-selecting process, where a senior leader has chosen to guide the career development of a junior colleague. Trust and shared interest are inherent in the relationship, and the senior leader cares deeply about the colleague's success. On the other hand, formal mentoring pairs often have the best intentions, but they rely on trust and shared interest being manufactured.

To challenge your natural inclinations, think about the person who you feel adds the greatest diversity to your team and ask yourself, "When was the last time I invited this person out for coffee or gave this person feedback on an assignment?" If your answers are consistent with the ones you would give for team members who are comfortably in your in-group, then you are on the right track. If not, inviting that person to get coffee or offering informal feedback on a project are solid steps in the right direction.

Inconsistent Response to Mistakes

Although everyone makes mistakes, how people respond to them makes all the difference. When employees in your organization slip up, do they get a second chance, or are they forever marked as careless? And would you answer that question the same way for each person on your staff?

Studies have shown that people are more likely to blame external factors when their in-group members make mistakes—for example, understanding that a report was late because the printer was broken. However, when out-group members make mistakes, people often attribute them to personal flaws—you can't blame the broken printer because there was plenty of time to complete the report.

A supervisor may be building a good relationship with one employee and at the same time ostracizing another with a penalty. When employees in out-groups notice that they are treated by the book while others are not, they perceive an environment that says discriminatory discipline is an unwritten rule of the workplace.

Bullying

Yelling, abusive emails, and attacks on another person's character are just some of the tactics workplace bullies use to wield power over others. Bullies target out-group members who seem vulnerable because they do not have strong informal mentors or allies. Managers should stop bullying because it can destroy a team and decreases productivity.

Insensitivity

Organizations often do not realize how changes in their employee and member demographics may require a few tweaks to their social traditions. Jokes, comments, and events that were traditional elements of the organization's culture may have a negative impact on a more diverse workforce. Insensitivity can become a source of workplace stress, causing burnout, low morale, and sometimes more serious consequences like drug use and violence. Ultimately, insensitivity can expose organizations to costly employment lawsuits. The manager who ignores complaints of insensitivity is just as guilty as the person who makes the offending comment or gesture.

Perceived Underperformance

People are influenced to act based on their beliefs, and their beliefs shape how they see the world, including their perceptions of other people. When you unconsciously believe that employees in an out-group are less skilled, less qualified, or less talented, you consciously look for affirmation of these beliefs.

If you start a relationship from the premise that an employee is not going to succeed, more often than not, that employee will not succeed. In the same way that work styles can obscure a manager's perceptions about an employee's abilities, visible characteristics can also distract managers from truly valuing the employee's work. Sometimes those who bring diversity to the office might not be appreciated because their managers and coworkers are considering the person doing the work and not the work itself. When your subjective perception about how someone will work interferes with objective assessment of his or her actual performance, everyone loses.

What can you do if you need help to address barriers? Training and other steps can move your organization in the right direction toward fully embracing D+I. Increased profits, improved reputation, and higher employee engagement are just a few of the huge returns you'll gain on the time and resources you invest in knocking down these five inclusion barriers.